Setting-up slide for stereo projectors



Jan. 12 1943- A D. L. BABcocK Erm. v2,307,981

SETTING-U1 SLIDE FOR STEREO PROJECTORS Filed Aug. 3, 1940 A TTORNEYS Patented Jan. 12, 1943 UNITED STATES PATENT OFFICE SETTING-UDP SLIDE FOR STEREO PROJECTORS David L. Babcock and Joseph L. Boon, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, Y., a xcorporation of New Jersey Appilcation August 3, 1940. fr'eai No. 350,690 6 (Ci. 88Z9) The present invention relates to stereo projecimage areas are also inverted. This reversed and tors, and more particularly to a settng-up slide inverted arrangement of the image areas is shown for such projectors. in Fig. 1 in connection with the setting-up slide One object of the invention is the provision of to be later more fully described.

a slide of this class which is formed with means In such a projector, the right-hand lens is used by which the position of the two light beams of to project; the image area or picture seen by the the projector may be properly adjusted on an left eye, and the left hand lens is used to project image receiving screen for stereo viewing. the image area or picture to be seen by the right Another object of the invention is the provieye. Since points intended to be seen at infinity sion on a slide of the class described" of separate lo should be separated by the inter-ocular distance adjusting indicating means or marks by which of the observer, and since the point to be seen both the vertical and lateral positions of the by the left eye should be the left point and the beams may be properly arranged for stereo view point to be seen by the right eye shouldgbe the ing on an image receiving screen. right point, it is necessary to adjust the optical Cal A .further object of the invention is the provi members of the projector so that the two light sion of a setting up slide of this kind which is beams cross between the projector and the screen extremely simple in construction, inexpensive to in order to give the required location of the two manufacture, and highly effective inuse. points to make the image appear at infinity. To these and other ends, the invention resides Since the separation of the points on the screen in certain improvements and combinations of 20 must be constant regardless of the projection parts all as will be hereinafter more fully dedistance, it is necessary to provide adjustment scribed, the novel features being pointed out in of the lenses to vary the amount of convergence the claims at the end of the specification. of the light beams in accordance with the screen In the drawing: distance.

Pig. 1 is a .thematic View of a stereo projector 25 rihe setting-up slide of the present invention and image receiving screen, showing the relation is adapted to help the projectionist to adjust the thereto of a setting-up slide constructed in aclenses properly. This setting up slide is genercordance with the preferred embodiment of the indicated by the numeral H and is adapted present invention; to be used in connection with a stereo projector Fig. 2 is a view of the setting up slide detached 30 shown schematically in Fig. 1, and comprising a from the PrOjector, and on a larger scale than pair of projection lamps l2 arranged in side-by that shown in Fig. l, showing the relation of the side relation, and condensing lenses I3 and obvarious adjustment indicating scales or marks on jective lenses I4 positioned on the optical axis of the slide; and thflamps l2. Suitable reflectors i8 are posi- Fig. 3 is a transverse sectional view through 35 tioned behind each of the lamps, asis well known the slide indicated in Fig. 2, showing the arrangepractice. The lenses I3 and I4 are adapted to ment of the various parts comprising in the slide. project a pair of light beams l5 and I6 onto a Similar reference numerals throughout the suitable image receiving or viewing screen I1 various views indicate the same parts. spaced from the projector and arranged in the The drawing shows a stereo projector of the 40 path of the light beams, the latter crossing over type in which the light beany cross over between between the projector and the screen so that the the projector and the viewing screen, as shown in images will be in proper relation on the screen, Fig. 1. Very often stereo image areas or transall of which is clearly illustrated in Fig. 1. parencies are mounted in a. slide for use in a hand In order to secure the desired stereo effect, it

viewer. The two image areas or transparencies 4 is essential that the position of the two light are mounted in such slides so that when placed beams on the screen be adjusted in accordance in the viewer, the right hand image area will he with the distance between the projector and the in alignment with the right eye of the user while screen. Each variation necessitates a. different the left hand image area will be in alignment variation in the convergence of the light beams with the left eye. When, however, such a slide 50 so as to properly maintain the latter in adjustis to be used in a projector, it is necessary to" ment for stereo viewing. There is, therefore, insert the slide in the projector so as to reverse a denite relation between the light beam conthe position of the image areas. In other words, vergence and the projector to scheen distance. the right image area is now on the left while the To facilitate the ready and easy adjustment of lei't imagearea is now at the right. The two 5 these light beams, the present invention provides Cal the setting-up slide II which is arranged in the projectork between the condenser lenses I3 and the objective lenses ld in the position to be occupied by the image carrying stereo slides to be used in the projector, as illustrated in Fig. 1.

This setting-up slide is of the same dimensions as the stereo slides which are to be viewed, and is formed of a pair of flat plate-like members 2| and 22 of any suitable material, preferably thin sheet metal, between which a strip of transparent sheet material 23 is arranged. These plates are also formed with a pair of registering viewing openings or apertures 24 which are in alignment with a pair of adjustment indicating scales or designations 25 formed on the .transparent sheet 23, as clearly shown in Fig. 2. These scales or designations comprise pairs of numerals which represent the various projector to screen distances, and are arranged lin the manner nearly shown in Fig. 2. when this snee is placed in the projector, it is arranged in the position shown in Fig. l in which the right-hand scale of Fig. 2 is at the left, and the left-hand scale is at the right, the scales also being inverted. The scales are positioned in the path of the two light beams I and I6 so that the latter will project the images from the numerals onto the screen Il, as shown in Fig. 1.

The various pairs of corresponding numerals of the scales 25 are so arranged on the slide that when the correct pair of numerals corresponding to the projector to screen distance are brought into superimposed or registering relation on the screen, the light beams I5 and IS will be in proper lateral adjustment on the screen for stereo viewing. For example, if the screen is spaced ten feet from the projector, the convergence of the light beams I5 and I6 is adjusted to bring the two numerals I@ of the scales 25 into superimposed or registering relation on the screen il, as shown in Fig. 1. When the two numerals I@ are thus positioned, the light beams i5 and it are in proper adjustment for a projector to screen distance of feet. j With such an adjustment, all the other numerals of the scales are out of registry, as shown in Fig. 1. Thus for each projector to screen distance, the proper set of numerals, corresponding to the distance then being used, are brought into superimposed or registering relation to properly adjust the light beams for stereo viewing. Such variations. or adjustments of the light beams may be secured by moving one of the objective lenses it, in any suitable and well-known manner. As such adjust ment means does not constitute a. part of the present invention, and is not necessary for a complete understanding thereof, the showing of such adjusting means is not deemed essential.

The above scales thus aiord a means by which the projectionist may readily and easily adjust the light beams in accordance with the projector to screen distance then being used. In some cases, however, it may be inconvenient to measure such distance, or the measuring means may not be readily available so that the proper projector to screen distance cannot be" definitely determined. To meet this condition, the present invention also provides an arrangement by which light beams may be accurately adjusted without knowing the distance between the projector to the screen. Obviously, in such cases the scales 25 are no longer suitable as their use depends on the projector to screen distance being known.

As pointed out above, points intended to be seen at infinity should be separated on the screen I'I the interocular distance of the observer. This distance is approximately 2% inches. Thus i! the infinity points are spaced this distance on the screen Il, the light beams will be properly adjusted for stereo viewing irrespective of the distance between the projector and screen. To secure this result, the transparent sheet 23 has suitably `formed thereon a pair of horizontally aligned opaque marks of indication 26, see Fig. 2t formed with central transparent areas 2'I, which are spaced on the sheet to correspond to the spacing of an infinity point in a pair of normal stereo images. These marks 26 and areas 21 are positioned in the path oil the two 4light beams I5 and I6 so that the latter may project the images of these marks onto the screen I1, as shown in Fig. l. Now if the convergence of the light beams I5 and i5 is adjusted so that the transparent areas El of the marks 26 are separated on a screen Il a distance of approximately 2/2 inches, the average interocular distance, the light beams will be in proper adjustment for stereo viewing. By means of this arrangement proper adjustment of the light beams may be secured without necessitating a knowledge of the distance between the screen and the projector.

While the above arrangement provides for the correct lateral adjustment of the two light beams, it is apparent that the two beams should also be in vertical alignment to secure the desired stereo eect, as is apparent. Tof secure such vertical adjustment, the sheet 23 is also formed with a thin elongated opaque reference mark or line 30 which is positioned adjacent and slightly above one of the scales 25, and is arranged to be insertedr in the path of only one of the light beams, such as the beam I6, so that the latter will project the image of the line onto the screen il, as shown in Fig. l. The sheet 23 is also formed with a second opaque reference mark 3| of the shape best shown in Fig. 2, and positioned adjacent the other scale 25. The second mark 3i is arranged in ,the path of the other light beam, the beam i5, so that the latter will project the image of the second mark into the screen il. The mark 3l is formed with a portion or section 32 of reduced area arranged in horizontal alient with the line or mark 30. It is now apparent that if the images of the line S and the reduced portion 32 are in registry or horizontal alignment on the screen il, as shown in Fig.

l, the two light beams are in proper verticaladjustment. If, however, the line 30 does not register with the portion 32 of the' mark 3|, .the light beams must be vertically adjusted to bring these1 portions into proper registry, as shown in Fig.

The above-described setting-up slide thus provides a means by which both lateral and vertical positioning of the light beams may be adjusted for stereo viewing. These various scales and marks thus ador-d an adjustment indicating means by which the projectionist may readily and easily secure vthe correct beam convergence in accordance with the projector .to screen distance. After the proper adjustments of the light beams have` been made, the setting-up slide II is removed from the projector, and may be replaced by slides containing stereo image areas which are then projected onto the viewing screen by the light beams I5 and I6 so as to secure the desired stereo viewing.

While one embodiment of the invention has been disclosed, it is to be understood that the inventive idea may be carried out in a number of ways. This application is therefore not tc be limited to the precise details described, but is intended to cover all variations and modiiications thereof falling within the scope of the appended claims.

We claim:

i. A setting up slide device formed of a pair of sheet like members supporting therebetween a strip of transparent sheet material, said sheet members being formed with pairs of aligned viewing openings for positioning in the separate beams of a stereo projector, pairs of similar adjustment indicating scales on said transparent sheet in said viewing openings, said scales having a plurality of pairs of numerals representing various projector to screen distances and positioned in said viewing openings on said slide to be projected in superimposed relation on said screen, the numerals of the two scales corresponding to the projector to screen distance then being used to indicate when the projecting-light beams are properly positioned relative to the screen for stereo viewing.

2. A setting up slide device formed of a pair of sheet like members supporting therebetween a strip of transparent sheet material, said sheet members being formed with pairs of aligned viewing openings for positioning in the separate beams of a stereo projector, an adjustment area on said transparent sheet in each of said viewing openings and positioned therein to be separately pro- `iected by the beams onto a viewing screen in a predetermined spaced horizontal relation thereon to indicate when the projecting light beams are properly adjusted laterally relative to the screen for stereo viewing.

3. A setting up slide device formed or a sheet like member supporting therebetween a strip of transparent sheet material, said sheet members being formed with pairs of aligned viewing openings tor positioning in the separate beams of a stereo projector, pairs or similar adjustment indicating scales on said transparent sheet in said viewing openings, said scales having a plurality of pairs of numerals representing various projector to screen distances and positioned in said viewing openings on said slide to be projected in superimposed relation on said screen, the numerals of the two scales corresponding to the projector to screen distance then being used to indicate when the projecting-light beams are properly positioned laterally relative to the screen for stereo viewing, and pairs of adjustment indicating reference marks on said slide and positioned in said viewing openings for projection by the projection beams in horizontal alignment to indicate when the projecting light beams are properly positioned vertically relative to the screen for stereo viewing.

4. A setting up slide device formed 0f a pair of sheet like members supporting therebetween a strip of transparent sheet material, said sheet members being formed with pairs of aligned viewing openings for positioning in the separate beams of a stereo projector, an adjustment area on said transparent sheet in each of said Viewing openings and positioned therein to be separately projected by the beams onto a viewing screen in a predetermined spaced horizontal relation thereon to indicate whenA the projecting light beams are properly adjusted laterally relative to the screen for stereo viewing, and pairs of adjustment indicating reference marks' on said slide and positioned in said viewing openings for projection by the projection beams in horizontal alignment to indicate when the projecting light beams are properly positioned vertically relative to the screen for stereo viewing.

5. A setting up slide device comprising a strip of transparent sheet material having portions thereof for positioning in the separate beams of a stereo projector, a pair of similar adjustment indicating indicia on said sheet and in the path of said beams to be projected thereby onto a viewing screen and when arranged in a predetermined relation on said screen to indicate that the projecting-light beams are properly adjusted laterally relative to the screen for stereo viewing.

6. A setting up slide device comprising a strip of transparent sheet material having portions thereof for positioning in the separate beams of a stereo projector, a pair of similar adjustment indicating indicia on said sheet and in the path of said beams to be projected thereby onto a viewing screen and when arranged in a predetermined relation on said screen to indicate that the projecting-light beams are properly adjusted laterally relative to the screen for stereo viewingl and pairs of vertical adjusting indicating reference marks on said slide and positioned in the path of said beams to be projected thereby onto said screen and when arranged in horizontal alignment to indicate that the beams are properly adjusted vertically relative to said screen for stereo viewing.

DAVID I i. BABCOCK. JOSEPH L. BOON. 

